WO2022264569A1

WO2022264569A1 - Method for producing valuable metal

Info

Publication number: WO2022264569A1
Application number: PCT/JP2022/011395
Authority: WO
Inventors: 雄山下
Original assignee: 住友金属鉱山株式会社
Priority date: 2021-06-15
Filing date: 2022-03-14
Publication date: 2022-12-22
Also published as: JP2022190869A; JP7215521B2; CA3222003A1; KR20240019266A; EP4357470A1; CN117441034A

Abstract

The present invention provides a method by which a valuable metal is able to be recovered with a high recovery rate by effectively and efficiently separating impurities, in particular iron, from a starting material to be processed.　A method for producing a valuable metal that contains cobalt (Co), the method comprising: a preparation step in which a starting material that contains at least iron (Fe) and a valuable metal is prepared; a melting step in which a melt is obtained by heating and melting the starting material, and the melt is subsequently formed into a molten material that contains an alloy and slag; and a slag separation step in which the slag is separated from the molten material, thereby recovering the alloy that contains the valuable metal. In the preparation step, the Fe/Co mass ratio in the starting material is controlled to 0.5 or less; and in the melting step, the Co content in the slag that is obtained by heating and melting the starting material is set to 1% by mass or less.

Description

Valuable metal manufacturing method

The present invention relates to a method for producing valuable metals from raw materials such as waste lithium ion batteries.

In recent years, lithium-ion batteries have become popular as lightweight, high-output batteries. A well-known lithium-ion battery has a structure in which a negative electrode material, a positive electrode material, a separator, and an electrolytic solution are enclosed in an outer can. Here, the outer can is made of metal such as iron (Fe) or aluminum (Al). The negative electrode material is composed of a negative electrode active material (graphite, etc.) adhered to a negative electrode current collector (copper foil, etc.). The positive electrode material is composed of a positive electrode active material (lithium nickelate, lithium cobaltate, etc.) adhered to a positive electrode current collector (aluminum foil, etc.). The separator is made of a polypropylene porous resin film or the like. Electrolyte solutions include electrolytes such as lithium hexafluorophosphate (LiPF ₆ ).

One of the major uses of lithium-ion batteries is hybrid and electric vehicles. Therefore, it is expected that a large amount of lithium-ion batteries installed in automobiles will be discarded in the future in accordance with the life cycle of automobiles. Also, some lithium-ion batteries are discarded as defective during manufacturing. Such used batteries and defective batteries produced during manufacturing (hereinafter referred to as "waste lithium ion batteries") are required to be reused as resources.

As a method of reuse, a pyrometallurgical refining process has been proposed in which the entire amount of waste lithium-ion batteries is melted in a high-temperature furnace (melting furnace). In the pyrometallurgical process, crushed waste lithium-ion batteries are subjected to a melting process to produce valuable metals to be recovered, represented by cobalt (Co), nickel (Ni), and copper (Cu), as well as iron and aluminum. It is a method of separating and recovering typical low value-added metals by utilizing the difference in oxygen affinity between them. In this method, metals with low added value are oxidized as much as possible to form slag, while valuable metals are recovered as alloys by suppressing their oxidation as much as possible.

In this way, in the pyrometallurgical process that separates and recovers valuable metals using the difference in oxygen affinity, it is very important to control the degree of redox during melting. In other words, if the degree of oxidation reduction is insufficiently controlled, there will be problems such as contamination of the alloy to be recovered as valuable metals with impurities, or incorporation of oxidized valuable metals into the slag that is to be recovered as impurities. This reduces the recovery of valuable metals. Therefore, in the pyrometallurgical process, conventionally, an oxidizing agent or reducing agent such as air or oxygen is introduced into the melting furnace to control the degree of redox.

For example, in US Pat. No. 5,400,000, the oxygen input to the bath is adjusted to 10 ⁻¹⁸ to 10 ⁻¹⁴ atm for a process for separating cobalt from lithium present in a charge containing lithium ion batteries or battery scrap. The target oxygen pressure is preferred, the upper oxygen pressure (10 ^-14 atm) eliminates the formation and loss of cobalt oxides in the slag, and the lower oxygen pressure (10 ^-18 atm) reduces aluminum and carbon (Claim 1 and [0018], etc.).

In addition, Patent Document 2 describes a method for recovering valuable metals from lithium-ion waste batteries containing nickel and cobalt. that it is possible to adjust the degree of oxidation, that almost the entire amount of aluminum oxide can be separated as slag in the slag separation process, that additional oxidation treatment is performed for a short time in the melting process, that the additional oxidation process can be finely It is stated that the degree of oxidation can be appropriately adjusted (Claim 1, [0033], [0036], etc.).

Japanese Patent No. 6542354 Japanese Patent No. 5853585

In this way, in the recovery of valuable metals in the pyrometallurgical process, it has been proposed to control the degree of redox by introducing air or oxygen during the melting process as a method of removing impurities. Issues remain in terms of separability. That is, it is necessary not only to control the oxidation-reduction degree (oxygen partial pressure) in the treatment in the melting process, but also to appropriately control the composition of the charge.

For example, waste lithium-ion batteries contain large amounts of impurities such as carbon (C), aluminum (Al), fluorine (F), phosphorus (P), and iron (Fe). Of these, iron has the property of being relatively easily reduced. Therefore, if the degree of reduction is excessively increased for recovering valuable metals, there is a risk that iron will be mixed into the alloy that should be recovered as valuable metals. On the other hand, if the degree of reduction is too low, iron can be oxidized and removed as slag, but valuable metals, particularly cobalt, are oxidized and cannot be recovered as alloys. Thus, it was difficult to completely separate iron and cobalt in the melting process, and either the quality of the alloy or the recovery rate of cobalt had to be sacrificed.

With the technique of Patent Document 1 mentioned above, although the recovery rate of cobalt is high due to the high degree of reduction, a large amount of iron also remains in the alloy. If the amount of iron brought into the treatment in the melting process is larger than that of cobalt, the amount of iron remaining in the alloy increases when trying to increase the recovery rate of cobalt. is required and the processing cost is high. Further, in the technique of Patent Document 2, a dephosphorization step is further provided after the melting step and the slag separation step, and phosphorus is separated from the alloy in the dephosphorization step (claim 1, [0039] ~[0046]). Phosphorus can be removed by such a method, and iron can also be removed to some extent, but the removal amount is not sufficient and a large amount remains in the alloy, which also necessitates removal treatment in a post-process. , the cost is also higher.

The present invention has been made in view of such circumstances, and is intended to effectively and efficiently separate impurities, especially iron, contained in raw materials to be treated, and recover valuable metals at a high recovery rate. The purpose is to provide a method that can

The inventor of the present invention has made extensive studies in order to solve the above-mentioned problems. As a result, with respect to iron (Fe), which is easily reduced next to cobalt (Co), the mass ratio of Fe/Co in the charge to be charged and treated in the melting process is limited, and the mass ratio obtained by the melting process is reduced. By controlling the cobalt content in the slag produced, the inventors have found that the iron content in the metal can be reduced while maintaining a high cobalt recovery rate, and have completed the present invention.

(1) A first invention of the present invention is a method for producing a valuable metal containing cobalt (Co), comprising the following steps; a preparation step of preparing a raw material containing at least iron (Fe) and a valuable metal; After heating and melting the raw material to form a melt, a melting step of making the melt into a melt containing an alloy and slag, and a slag separating the slag from the melt and recovering the alloy containing valuable metals. and a separation step, wherein the preparation step controls the mass ratio of Fe/Co in the raw material to 0.5 or less, and the melting step controls the Co grade in the slag obtained by heating and melting the raw material. is 1% by mass or less, a method for producing a valuable metal.

(2) A second aspect of the present invention is a method for producing a valuable metal according to the first aspect, wherein the Fe content in the alloy obtained by heating and melting the raw materials is 5% by mass or less.

(3) A third aspect of the present invention is a method for producing a valuable metal according to the first or second aspect, wherein the raw material includes waste lithium ion batteries.

(4) A fourth aspect of the present invention is a method for producing a valuable metal according to the third aspect, wherein the outer can used in the waste lithium ion battery contains iron.

(5) A fifth aspect of the present invention is the method according to any one of the first to fourth aspects, wherein the Co in the slag is It is a method for producing valuable metals that adjusts the grade.

According to the present invention, it is possible to provide a method capable of effectively and efficiently separating impurities, especially iron, contained in raw materials to be treated, and recovering valuable metals at a high recovery rate.

It is a process drawing which shows the flow which manufactures a valuable metal from a waste lithium ion battery.

A specific embodiment of the present invention (hereinafter referred to as "this embodiment") will be described below. In addition, the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention.

≪1. Methods for producing valuable metals≫
The method of producing valuable metals according to the present embodiment is a method of separating and recovering valuable metals including cobalt (Co) from raw materials containing valuable metals. Therefore, it can also be called a recovery method for valuable metals. The method according to the present embodiment is mainly a method by a pyrometallurgical process, but may be composed of a pyrometallurgical process and a hydrometallurgical process.

Specifically, the method according to the present embodiment includes the following steps; a step of preparing a charge containing at least iron (Fe) and a valuable metal as a raw material (preparation step); After forming the melt into a melt, there is a process of converting the melt into a melt containing an alloy and slag (melting process), and a process of separating the slag from the resulting melt and recovering the alloy containing valuable metals (slag separation step). This method is characterized by limiting the Fe/Co mass ratio in the raw material in the preparation step and controlling the Co grade in the slag obtained by heating and melting the raw material in the melting step.

Here, the valuable metals are those to be recovered, and include at least cobalt (Co) as described above. More specifically, for example, it is at least one metal or alloy selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), and combinations thereof.

[Preparation process]
In the preparation step, a charge containing valuable metals is prepared as a raw material. The charged material, which is a raw material, is a target of treatment for recovering valuable metals, and contains valuable metals including cobalt (Co) in addition to containing at least iron (Fe) as impurities. The charge may contain these components in the form of metals or elements, or in the form of compounds such as oxides. In addition, the charge may contain other inorganic or organic components other than these components.

In the method according to the present embodiment, in the preparation step, the mass ratio (Fe/Co) of iron (Fe) to cobalt (Co) in the raw material is controlled within a specific range. Specifically, the mass ratio of Fe/Co in the raw material is controlled to 0.5 or less.

If the mass ratio of Fe/Co in the raw material is greater than 0.5, it becomes difficult to separate cobalt and iron in the melting process, which will be described later, and the quality of iron contained in the alloy obtained by the melting process increases. By limiting the Fe/Co mass ratio in the preparation step, the iron grade in the resulting alloy can be reduced. Specifically, the method for adjusting the mass ratio of Fe/Co in the raw material is not particularly limited. For example, the raw material is subjected to treatments such as crushing and magnetic separation to remove iron-containing members. can do.

The raw material is not particularly limited. Examples include waste lithium-ion batteries, electronic components containing dielectric materials or magnetic materials, and electronic equipment. Also, the form is not limited as long as it is suitable for the treatment in the subsequent steps. Moreover, the raw material may be adjusted to a suitable form by performing a treatment such as pulverization. Furthermore, unnecessary components such as moisture and organic matter may be removed by subjecting the raw material to heat treatment, separation treatment, or the like.

[Melting process]
In the melting process, the prepared raw material (charge) is charged into a melting furnace, subjected to a heat melting process to form a melt, and then the melt is made into a melt containing an alloy (metal) and slag. .

The melt contains the alloy and slag in a molten state. The melt also includes the alloy and the slag, each in a molten state. The alloy mainly contains valuable metals, and the slag contains other components including impurity elements. Therefore, it becomes possible to separate the valuable metals and the other components respectively as the alloy and the slag. This is because metals with low added value (such as Al) have high affinity for oxygen, whereas valuable metals have low affinity for oxygen.

For example, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are commonly Generally, they are oxidized in the order of Al>Li>C>Mn>P>Fe>Co>Ni>Cu. That is, aluminum (Al) is most easily oxidized, and copper (Cu) is most difficult to oxidize. Therefore, metals with low added value (such as Al) are easily oxidized into slag, and valuable metals (Cu, Ni, Co) are reduced into alloys. In this way, valuable metals and low value-added metals can be separated in the form of alloys and slag, respectively.

Here, as can be seen from the above explanation of the relationship of oxygen affinity, iron (Fe) is relatively difficult to be oxidized among impurity elements with low added value, in other words, it is easily reduced, and its properties are valuable. It is similar to cobalt (Co), which is a metal. Therefore, it is difficult to sufficiently effectively separate iron and cobalt with conventional redox control in the melting process.

Therefore, in the method according to the present embodiment, as described above, the mass ratio of Fe/Co in the raw material is limited to 0.5 or less in the preparation step, and the raw material is charged into the melting step. . In the melting step, the Co grade in the slag obtained by heat melting the raw material is used as an indicator of the degree of reduction. Specifically, the degree of reduction is controlled so that the Co grade in the slag is 1% by mass or less. do. This makes it possible to reduce Fe in the obtained alloy while maintaining a high Co recovery rate, and as a result, it is possible to efficiently recover valuable metals.

The degree of reduction is controlled by sampling the obtained slag, analyzing the Co grade, and determining whether the Co grade is 1% by mass or less. For example, if the Co grade in the slag exceeds 1% by mass, control is performed to increase the degree of reduction by adding a reducing agent. The method for confirming the Co grade in the slag is not particularly limited, and examples thereof include a method of sampling the slag, pulverizing it, and confirming it with a fluorescent X-ray analyzer. Alternatively, the relationship between the Co grade in the slag and the oxygen concentration in the melt may be confirmed in advance, and the Co grade may be checked by measuring the oxygen concentration in the melt with an oxygen sensor.

In controlling the degree of reduction using the grade of Co in the slag as an index, a method of increasing the degree of reduction (shifting to the reduction side) or a method of decreasing the degree of reduction (shifting to the oxidation side) may be performed by a known method. For example, there is a method of introducing a reducing agent or an oxidizing agent into the raw material to be subjected to the heating and melting process or into the melt obtained by melting the raw material. As the reducing agent, a material having a high carbon grade (graphite powder, graphite grains, coal, coke, etc.), carbon monoxide, or the like can be used. A component having a high carbon grade among the raw materials to be subjected to the heat melting process can also be used as a reducing agent. As the oxidizing agent, an oxidizing gas (air, oxygen, etc.) or a material with a low carbon grade can be used. A component having a low carbon grade among the raw materials to be subjected to the heat melting process can also be used as the oxidizing agent.

Also, the method of introducing the reducing agent and the oxidizing agent may be performed by a known method. For example, if the reducing agent or oxidizing agent is a solid substance, it can be introduced by putting it into the raw material or melt. When the reducing agent or oxidizing agent is a gaseous substance, it can be introduced by blowing it through an inlet such as a lance provided in the melting furnace. In addition, the timing of introduction of the reducing agent and oxidizing agent is not particularly limited. Alternatively, a reducing agent or an oxidizing agent may be introduced at the stage when the raw materials are melted to form a melt.

Flux may be added to the raw material during the heat melting process. By adding flux, the melting temperature can be lowered, and the removal of phosphorus (P), which is an impurity element, can be further promoted. The flux preferably contains an element that takes in impurity elements to form a basic oxide with a low melting point. For example, since phosphorus is oxidized to an acidic oxide, the more basic the slag formed by heating and melting, the easier it is to incorporate phosphorus into the slag and remove it. Among them, those containing calcium compounds that are inexpensive and stable at room temperature are more preferable. Examples of calcium compounds include calcium oxide (CaO) and calcium carbonate (CaCO ₃ ).

Although the heating temperature for heating and melting the raw materials is not particularly limited, it is preferably 1300°C or higher and 1600°C or lower. By setting the heating temperature to 1300° C. or higher, the valuable metals (eg, Cu, Co, Ni) are sufficiently melted to form an alloy with enhanced fluidity. As a result, it becomes possible to efficiently separate the alloy and the slag in the slag separation step, which will be described later. Moreover, it is more preferable to set the heating temperature to 1350° C. or higher. On the other hand, if the heating temperature exceeds 1600° C., thermal energy is wasted and refractories such as the crucible and furnace walls are rapidly worn, which may reduce productivity.

[Preheating step]
If necessary, a step (preheating step) may be provided before the melting step to preheat (oxidize and roast) the raw material to obtain a preheated product (oxidized roast).

In the preheating process (oxidizing roasting process), the amount of carbon contained in the raw material to be supplied to the melting process is reduced by preheating the raw material. By providing such a preheating step, even if the raw material to be subjected to the melting step contains excessive carbon, the carbon can be effectively oxidized and removed, and the heating and melting in the subsequent melting step can be performed. can promote alloy integration of valuable metals in the processing of

More specifically, in the heating and melting process in the melting process, the valuable metal is reduced and becomes locally molten fine particles. It can be a physical obstacle. If the agglomeration and integration of molten fine particles is hindered, the separation of the produced alloy and slag may be hindered, resulting in a decrease in the recovery rate of valuable metals. On the other hand, by preheating the raw material in the preheating process to remove the carbon prior to the heat melting process, the aggregation and integration of the molten fine particles can be efficiently advanced, and the recovery rate of the valuable metal can be improved. It is possible to raise it further. In addition, since phosphorus is an impurity element that is relatively easily reduced, if carbon is excessively present in the raw material, phosphorus may be reduced and incorporated into the alloy together with the valuable metal. In this respect as well, by removing excess carbon in the raw material in advance by preheating, it is possible to prevent phosphorus from being mixed into the alloy.

The carbon content of the preheated product (oxidized roasted product) obtained by preheating is preferably less than 1% by mass.

In addition, by providing a preheating process, it is possible to suppress variations in oxidation. The preheating treatment in the preheating step can be performed at an oxidation degree (oxidative roasting) that can oxidize low-value-added metals (such as Al) contained in the raw material to be subjected to the melting step. desirable. On the other hand, the degree of oxidation can be easily controlled by adjusting the treatment temperature, time and/or atmosphere of preheating. Therefore, in the preheating process, the degree of oxidation can be adjusted more strictly, and variations in oxidation can be suppressed.

The degree of oxidation is adjusted as follows. As mentioned above, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) are , generally in the order of Al>Li>C>Mn>P>Fe>Co>Ni>Cu. In the preheating step, if aluminum (Al) is contained in the raw material, oxidation is allowed to progress until all of the Al is oxidized. Oxidation may be accelerated until some of the iron (Fe) is oxidized, but it is preferable to limit the degree of oxidation to such an extent that cobalt (Co) is not oxidized and distributed to the slag.

The preheating process is preferably carried out in the presence of an oxidizing agent. As a result, carbon (C), which is an impurity element, can be efficiently removed by oxidation. The oxidizing agent is not particularly limited, but an oxygen-containing gas (air, pure oxygen, oxygen-enriched gas, etc.) is preferable because it is easy to handle. Moreover, the amount of the oxidizing agent to be introduced is preferably, for example, about 1.2 times the chemical equivalent required for oxidizing each substance to be oxidized.

The heating temperature for preheating is preferably 700°C or higher and 1100°C or lower. If the temperature is 700° C. or higher, the oxidation efficiency of carbon can be further increased, and the oxidation time can be shortened. Further, by setting the temperature to 1100° C. or less, the thermal energy cost can be suppressed and the efficiency of preheating can be improved. Also, the preheating temperature may be 800° C. or higher or 900° C. or lower.

The preheating process can be performed using a known roasting furnace. Moreover, it is preferable to use a furnace (preliminary furnace) different from the melting furnace used in the subsequent melting process, and to carry out the treatment in the preliminarily furnace. As the preheating furnace, any type of furnace can be used as long as it is a furnace capable of performing an oxidation treatment inside by supplying an oxidizing agent (such as oxygen) while roasting the raw material to be treated. Examples include conventionally known rotary kilns and tunnel kilns (Haas furnaces).

[Slag separation process]
In the slag separation step, slag is separated from the melt obtained by heating and melting in the melting step to recover an alloy containing valuable metals. In the melt, the alloy and slag have different specific gravities. Therefore, the slag having a lower specific gravity than the alloy gathers in the upper part of the alloy, and the slag can be easily separated and recovered by specific gravity separation. Alternatively, the molten material containing the alloy and slag is discharged into a mold or the like, and after the alloy and slag are separated and solidified in the mold due to the difference in specific gravity, the upper slag is removed and the solidified alloy is recovered. good.

After the slag is separated in the slag separation step, a sulfurization step of sulfurizing the obtained alloy or a pulverization step of pulverizing the obtained sulfide or alloy may be provided. Further, alloys of valuable metals obtained through such pyrometallurgical processes may be subjected to hydrometallurgical processes. By the hydrometallurgical process, impurity components can be further removed, valuable metals (eg, Cu, Ni, Co) can be separated and refined, and each of them can be recovered. Examples of treatments in the hydrometallurgical process include known techniques such as neutralization treatment and solvent extraction treatment.

As described above, in the method for producing a valuable metal according to the present embodiment, the mass ratio of Fe/Co in the raw material to be subjected to the heat melting process is limited in the preparation step, and the Co in the slag obtained in the melting step The quality is controlled and heat melting is applied. According to such a method, the Fe grade in the alloy (metal) can be reduced while maintaining a high cobalt recovery rate, and valuable metals can be recovered more efficiently. Specifically, for example, the Fe content of the alloy can be reduced to 5% by mass or less while maintaining the cobalt recovery rate at 90% or more.

Here, the "cobalt recovery rate" is calculated according to the following formula (1) using the finally obtained alloy and the content of cobalt contained in the slag.

In the method according to the present embodiment, the raw material (charge) is not particularly limited as long as it contains at least a valuable metal including cobalt (Co), but it is preferably a raw material containing waste lithium ion batteries. . Waste lithium-ion batteries contain lithium (Li) and valuable metals (Cu, Ni, Co), as well as metals with low added value (Al, Fe, etc.) and carbon components. Therefore, by using raw materials including waste lithium ion batteries, valuable metals can be efficiently separated and recovered. "Waste lithium-ion batteries" refers not only to used lithium-ion batteries, but also to defective products such as positive electrode materials that make up the battery during the manufacturing process, residues inside the manufacturing process, and lithium-ion waste such as generated scraps. This is a concept that includes waste materials in the battery manufacturing process. Therefore, waste lithium ion batteries can also be called lithium ion battery waste materials.

Below, we will explain how to manufacture valuable metals from waste lithium-ion batteries.

≪2. Method for producing valuable metals from waste lithium-ion batteries>>
FIG. 1 is a process diagram showing an example of the flow of a method for producing valuable metals from waste lithium ion batteries. As shown in FIG. 1, this method includes a step of removing the electrolytic solution and outer can of the waste lithium ion battery to obtain the waste battery contents (waste battery pretreatment step S1), and pulverizing the waste battery contents. A step of forming a pulverized product (pulverizing step S2), a step of preheating the pulverized product into a preheated product (preheating step S3), and a step of melting the preheated product into a molten product (melting step S4). and a step of separating slag from the melt and recovering the alloy (slag separation step S5). Further, although not shown, after the slag separation step S5, a sulfurization step of sulfurizing the obtained alloy and a pulverization step (second pulverization step) of pulverizing the obtained sulfide or alloy may be provided.

Waste lithium-ion batteries contain valuable metals such as nickel (Ni), cobalt (Co), and copper (Cu). Further, the waste lithium ion battery contains iron (Fe) as a constituent material of an outer can, which will be described later, for example. Through the treatment in each step shown in FIG. 1, it is possible to effectively recover valuable metals while separating impurity elements such as iron.

[Waste battery pretreatment process, pulverization process]
(Waste battery pretreatment process)
The waste battery pretreatment step S1 is performed for the purpose of preventing the waste lithium ion battery from exploding and rendering it harmless, and removing the outer can. Since the lithium ion battery is a closed system, it contains an electrolytic solution and the like inside. Therefore, if the pulverization process is performed as it is, there is a risk of explosion, which is dangerous. It is preferable to perform discharge treatment or electrolytic solution removal treatment by some method.

In addition, outer cans that constitute lithium-ion batteries are often made of metals such as aluminum (Al) and iron (Fe), and such metal outer cans are relatively easy to collect as they are. is.

In this way, by removing the electrolyte and the outer can in the waste battery pretreatment step S1, it is possible to improve safety and increase the recovery rate of valuable metals (Cu, Ni, Co).

The specific method of waste battery pretreatment is not particularly limited. For example, there is a method of physically opening a hole in a waste lithium ion battery with a needle-like cutting edge to remove the electrolyte. Another method is to heat the waste lithium ion battery to burn the electrolytic solution to render it harmless.

In the waste battery pretreatment step S1, when recovering aluminum and iron contained in the outer can, after pulverizing the removed outer can, the pulverized material may be sieved using a sieve shaker. Since aluminum can be easily pulverized by light pulverization, it can be efficiently recovered. Alternatively, the iron contained in the outer can may be recovered by magnetic separation.

(Pulverization process)
In the pulverization step S2, the content of the waste lithium ion battery is pulverized to obtain a pulverized material. This step is intended to increase the reaction efficiency in the pyrometallurgical process. By increasing the reaction efficiency, the recovery rate of valuable metals (Cu, Ni, Co) can be increased.

The specific crushing method is not particularly limited. It can be pulverized using a conventionally known pulverizer such as a cutter mixer.

Here, the waste battery pretreatment step S1, or the waste battery pretreatment step S1 and the crushing step S2 correspond to the preparatory steps described above. That is, the method according to the present embodiment is characterized by controlling the mass ratio (Fe/Co) of iron (Fe) to cobalt (Co) in the raw material to 0.5 or less. By limiting the mass ratio of Fe/Co in this way, it is possible to reduce the iron grade in the alloy (metal) obtained through the heating and melting treatment in the melting step S4, which will be described later.

[Preheating step]
In the preheating step (oxidizing roasting step) S3, the pulverized product obtained in the crushing step S2 is preheated (oxidizing roasting) to obtain a preheated product (oxidizing roasting product). The details of this step are as described above, and by preheating in the preheating step, even if the raw material supplied to the melting step S4 contains excessive carbon, the carbon is effectively removed by oxidation. and can promote the alloying integration of the valuable metals in the heat-melting process.

[Melting process]
In the melting step S4, the preheated material obtained in the preheating step S3 is melted to obtain a molten material. The details of this step are as described above.

In particular, in the method according to the present embodiment, a raw material having an Fe/Co mass ratio of 0.5 or less is charged into a melting furnace and subjected to a heat melting process, and the heat melting process is performed to obtain Using the Co grade in the slag as an index of the degree of reduction, specifically, the reduction degree is controlled so that the Co grade in the slag is 1% by mass or less. This makes it possible to reduce Fe in the obtained alloy while maintaining a high Co recovery rate, and as a result, it is possible to efficiently recover valuable metals.

[Slag separation process]
In the slag separation step S5, slag is separated from the melt obtained in the melting step S4 to recover the alloy (metal). The details of this process are as described above, and the metal and the slag can be easily separated and recovered due to the difference in their specific gravities.

Note that, as described above, the sulfurization process and the pulverization process may be provided after the slag separation process S5. Alternatively, each valuable metal may be separated and refined by subjecting an alloy containing the recovered valuable metal to a hydrometallurgical process.

Examples of the present invention will be described below in more detail, but the present invention is not limited to the following examples.

(1) Production of Valuable Metal Using waste lithium ion batteries as a raw material (injection), the following steps were sequentially carried out to produce valuable metals.

[Waste battery pretreatment process, pulverization process (preparation process)]
Used batteries and defective products collected in the battery manufacturing process were prepared as waste lithium ion batteries as raw materials. The waste lithium ion batteries were collectively immersed in salt water to discharge, then moisture was removed, and the batteries were roasted at 260° C. in the air to remove the electrolyte to obtain battery contents.

The resulting battery content was pulverized with a pulverizer (trade name: Good Cutter, manufactured by Ujiie Seisakusho Co., Ltd.) to obtain a pulverized product. Iron was removed from the pulverized material obtained by using a sieve and a magnet, and the mass ratio of Fe/Co in the raw material was adjusted to a predetermined value shown in Table 1 below.

[Preheating step]
The pulverized material thus obtained was put into a rotary kiln and preheated in the atmosphere at 800° C. for 180 minutes to obtain a preheated material (raw material for heating and melting).

[Melting process]
Calcium oxide (CaO) as a flux and graphite powder as a reducing agent were added to the preheated pulverized material (raw material for heat melting) and mixed. The resulting mixture was charged into an alumina crucible with a capacity of 1 L and heated and melted at a temperature of 1400° C. by resistance heating to form a melt. After that, a melt containing the fusion metal and slag was obtained.

During the heat melting, the generated slag is sampled to analyze the Co grade, and if the Co grade exceeds 1% by mass, a reducing agent is added to control the degree of reduction, and the slag is was made to have a Co grade of 1% by mass or less.

[Slag separation process]
The slag was separated from the obtained melt by utilizing the difference in specific gravity, and the alloy (metal) was recovered.

(2) Evaluation The recovered alloy (metal) was subjected to elemental analysis using an ICP analyzer (Agilent5100SUDV, manufactured by Agilent Technologies). Nickel (Ni), cobalt (Co), and copper (Cu), which are valuable metals, and iron (Fe), which is an impurity that is difficult to remove from metals, were the elements to be analyzed. Also, the content (% by mass) of iron in the alloy was defined as the iron grade (Fe grade).

Also, the recovery rate of cobalt was determined as follows. That is, it was calculated according to the following formula (1) using the content of cobalt in the alloy and slag determined by elemental analysis.

(3) Results Table 1 below shows the Fe grade in the alloy and the Co recovery rate.

As can be seen from the results in Table 1, in Examples 1 to 7, the Co recovery rate is 90% or more, and the Fe quality in the alloy is 5% by mass or less, resulting in a high Co recovery rate and a reduction in the Fe quality in the alloy. was able to reconcile

On the other hand, in Comparative Example 1, although the Co recovery rate was high, the Fe content in the alloy exceeded 5% by mass. This is thought to be due to the high Fe/Co ratio in the raw material, and therefore, when the degree of reduction is increased for the purpose of achieving a high Co recovery rate, Fe is also reduced, resulting in an increase in the Fe grade in the alloy. Moreover, in Comparative Examples 2 and 3, although the Fe grade in the alloy was reduced, the Co recovery rate was less than 90%. In Comparative Example 2, since the Fe/Co ratio in the raw material was high, if the degree of reduction was lowered for the purpose of reducing the Fe grade in the alloy, the reduction of Co did not progress, and as a result, the Co recovery rate was low. Also in Comparative Example 3, if the degree of reduction was lowered for the purpose of reducing the Fe grade in the alloy, the reduction of Co did not proceed, and as a result, the Co recovery rate was low.

Claims

A method for producing valuable metals including cobalt (Co), comprising the steps of;
a preparation step of preparing a raw material containing at least iron (Fe) and a valuable metal;
a melting step of heating and melting the raw material to form a melt, and then converting the melt into a melt containing an alloy and slag;
a slag separation step of separating slag from the melt and recovering an alloy containing valuable metals;
has
In the preparation step, the mass ratio of Fe/Co in the raw material is controlled to 0.5 or less,
In the melting step, the Co grade in the slag obtained by heating and melting the raw material is set to 1% by mass or less,
A method for producing valuable metals.
The Fe grade in the alloy obtained by heating and melting the raw material is 5% by mass or less.
The method for producing a valuable metal according to claim 1.
The raw material includes waste lithium ion batteries,
3. The method for producing a valuable metal according to claim 1 or 2.
The outer can used in the waste lithium ion battery contains iron.
The method for producing a valuable metal according to claim 3.
In the melting step, the Co grade in the slag is adjusted by adding an oxidizing agent and/or a reducing agent to the melt.
5. The method for producing a valuable metal according to any one of claims 1 to 4.